Senescence in Podospora anserina is maternally inherited and some races senesce more rapidly than others. During senescence, certain regions of the mitochondrial genome, termed senDNAs, amplify and suppress the replication of the non-senescent genome. Alpha senDNA, the first discovered, occurs most frequently and is found even in young cultures of race A, the most rapidly senescing race. DNA sequence analysis has shown that Alpha senDNA is a class II intron of the COI gene. Other senDNAs, for example Beta and Epsilon senDNA do not contain class II introns; Epsilon senDNA does contain class I introns in the URFI gene, one of which is self-splicing. Others have shown that certain class II introns, including Alpha senDNA contain putative amino acid sequences homologous to reverse transcriptase. Race A but not race s has a second class II intron close to Alpha senDNA in the COI gene which also has homology to reverse transcriptase. Our general objective is to relate the amplification of these senDNAs to senescence. We have two specific aims. 1. Investigate the Senescent Phenotype. Utilizing either outgrowth from senescent mycelia or specific mutagens, we have isolated certain phenotypes exhibiting altered growth characteristics. Restriction enzyme analysis has shown that gene rearrangements occur. We now wish to study the general nature of these mitochondrial gene rearrangements using specific probes and relate them to the senescent phenotype. 2. Study the Molecular Biology of Senescence. Race A has two class II introns in the COI gene whereas race s has but one. Are there other class II introns encoding reverse transcriptase? Using consensus sequences of class II introns will enable us to identify circular transcripts as well as their location on the genome. DNA sequence analysis will identify the reverse transcriptase homologue. We also wish to localize the reverse transcriptase activity found in older cultures. In no other system is there such a clearly developed link between molecular events and senescence. Gene rearrangements play a critical role in many developmental processes and the connection with reverse transcriptase provides significant relevance with many health related areas.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG006320-02
Application #
3117283
Study Section
Molecular Cytology Study Section (CTY)
Project Start
1986-09-01
Project End
1989-08-31
Budget Start
1987-09-01
Budget End
1988-08-31
Support Year
2
Fiscal Year
1987
Total Cost
Indirect Cost
Name
University of Colorado Denver
Department
Type
Schools of Medicine
DUNS #
065391526
City
Aurora
State
CO
Country
United States
Zip Code
80045
Cummings, D J; Michel, F; Domenico, J M et al. (1990) DNA sequence analysis of the mitochondrial ND4L-ND5 gene complex from Podospora anserina. Duplication of the ND4L gene within its intron. J Mol Biol 212:269-86
Silliker, M E; Cummings, D J (1990) A mitochondrial DNA rearrangement and three new mitochondrial plasmids from long-lived strains of Podospora anserina. Plasmid 24:37-44
Silliker, M E; Cummings, D J (1990) Genetic and molecular analysis of a long-lived strain of Podospora anserina. Genetics 125:775-81
Cummings, D J; Michel, F; Domenico, J M et al. (1990) Mitochondrial DNA sequence analysis of the cytochrome oxidase subunit II gene from Podospora anserina. A group IA intron with a putative alternative splice site. J Mol Biol 212:287-94
Cummings, D J; Michel, F; McNally, K L (1989) DNA sequence analysis of the apocytochrome b gene of Podospora anserina: a new family of intronic open reading frame. Curr Genet 16:407-18
Cummings, D J; Michel, F; McNally, K L (1989) DNA sequence analysis of the 24.5 kilobase pair cytochrome oxidase subunit I mitochondrial gene from Podospora anserina: a gene with sixteen introns. Curr Genet 16:381-406
Cummings, D J; Domenico, J M; Nelson, J (1989) DNA sequence and secondary structures of the large subunit rRNA coding regions and its two class I introns of mitochondrial DNA from Podospora anserina. J Mol Evol 28:242-55
Cummings, D J; Domenico, J M; Nelson, J et al. (1989) DNA sequence, structure, and phylogenetic relationship of the small subunit rRNA coding region of mitochondrial DNA from Podospora anserina. J Mol Evol 28:232-41
Cummings, D J; Domenico, J M (1988) Sequence analysis of mitochondrial DNA from Podospora anserina. Pervasiveness of a class I intron in three separate genes. J Mol Biol 204:815-39
Turker, M S; Domenico, J M; Cummings, D J (1987) Excision-amplification of mitochondrial DNA during senescence in Podospora anserina. A potential role for an 11 base-pair consensus sequence in the excision process. J Mol Biol 198:171-85